The Louisiana Department of Transportation and Development's Huey P. Long U.S. 90 Bridge over the Mississippi River is a key infrastructure component of the New Orleans and Louisiana economies, with 50,000 vehicles daily, along with passenger and freight train usage. Completed in 1935, the steel truss bridge supports 2 railroad tracks, and 4 narrow 9-foot wide traffic lanes.
This Massman-led joint venture project added trusses on each side and replaced the existing traffic lanes with 3 widened lanes and shoulders. The main span is 2,375 feet long in 4 spans. The widening scope included over 17,000 tons of structural steel, and extensive retrofitting of the existing trusses to accept connections to the new trusses.
Extensive work procedures were also employed at the road deck level to maintain the normal 4 lanes of traffic and rail usage as much as possible. The retrofitting and connection work on the existing trusses was performed from fixed work platforms, and also moving platforms over the traffic lanes.
The widening project also required improvements to the bridge substructure as well as the bridge approaches. The location and scope of this effort presented several challenges to the Massman team. Crane barge access in the main river channel required constant coordination with Mississippi River shipping and barge operators. The river depths approached 90 feet which required substantial anchoring of crane barges. Work was suspended for several extended periods due to river flood stages and tropical storms. The river currents and swift eddies near the piers required divers and marine equipment to operate safely.
In addition to the main span, the bridge structure for vehicular traffic includes the 4,700-foot east approach and the 5,600-foot west approach, as well as associated ramp work at both ends. The approach structures consists of 200 pile supported concrete piers with precast girders and cast-in-place deck, with the high rise portion supported by a four-span widened structural steel truss about 150 feet above the river.
Below is a video of the Huey P. Long bridge project truss lift.